The present invention relates to a midplane to which circuit boards of a data processing apparatus are mounted.
It is known in the art relating to the manufacture of data processing devices, such as routers, to use a midplane architecture for interconnecting circuit boards. In the specific example of a router, a set of port circuit boards connects to a set of switching circuit boards through a midplane. The midplane is itself a circuit board with two main surfaces. The port circuit boards are mounted to one main surface of the midplane while the switching circuit boards are mounted to the other surface of the midplane. The midplane establishes electrical pathways between the main surfaces such that data signals from the port circuit boards can travel to the switching circuit boards.
Known midplane structures have a series of insulating layers on which are formed patterns of electrical conductors by photolithography. Vias interconnect electrical conductors on different layers, when such interconnection is necessary.
One drawback of this prior art midplane design is the poor signal transmission performance when the signals exchanged between the port and switching circuit boards are high data rare signals. One possible approach to alleviate this drawback is to use special driver circuits on the circuit boards to condition the signals and compensate for possible corruption generated during the transmission, however this approach is not entirely satisfactory.
Against this background, the need to conceive an improved midplane design that offers a superior signal transmission performance, by comparison to prior art designs, is clearly apparent.
Under a first broad aspect, the invention provides a data processing apparatus, having a first plurality of circuit boards arranged generally side-by-side and a second plurality of circuit boards arranged generally side-by-side, the first plurality of circuit boards being mounted to the second plurality of circuit boards by a midplane. The midplane has a first main surface, a second main surface and a plurality of connector elements, each connector element including an array of electrical couplers that extend generally transversally to the main surfaces of the midplane. The array of electrical couplers connect data contacts on one circuit board mounted to the first surface of the midplane to data contacts of another circuit board mounted to the second surface of the midplane. The connection between the circuit boards is such that each data contact on one circuit board and the corresponding data contact of the other circuit board are in physical contact with a common electrical coupler.
The advantage of this design resides in the improved signal propagation performance that results from the direct connection between corresponding data contacts through common electrical couplers.
In a specific and non-limiting example of implementation, the electrical couplers are in the form of vias. Alternatively, the electrical couplers are in the form of pins projecting from the main surfaces of the midplane. It is also possible to use electrical couplers that are in the form of vias on one of the main surfaces of the midplane and in the form of pins projecting from the other main surface.
Under a second broad aspect, the invention provides a midplane for a data processing apparatus. The midplane has a generally planar body defining a first main surface and a second main surface. A void area extends from the first main surface to the second main surface. Connectors are formed on both main surfaces and they are remote from the void area. The connectors on each main surface are capable of engaging circuit boards. The connectors layout is such that the circuit boards; on each main surface are side-by-side and the circuit boards on the first main surface are in a non-parallel relationship with the circuit boards on the second main surface. In one form of implementation, the connectors are electrical connectors, and establish electrical connections with terminals on the circuit boards. In addition to their electrical connection capability, the electrical connectors also provide a mechanical fastening function to retain the circuit boards to the midplane. More specifically, each electrical connector is in the form of a socket that receives a mating tongue formed on the corresponding circuit board, the socket arid tongue having mating electric terminals that physically contact one another to establish the electrical connection. Note that the gender can be reversed without departing from the spirit of the invention, more specifically, the electrical connectors can be in the form of projecting tongues that engage corresponding sockets on the circuit boards. Another possibility is to provide connectors without electrical connection function such connectors provide only a mechanical fastening function. Yet, another possibility is to provide connectors that offer only electrical connection function without a mechanical fastening function. Under this realization, the circuit boards are fastened to the midplane by an agency independent from the electrical connectors.
Under another aspect, the invention provides a data processing apparatus, having a first plurality of circuit boards arranged generally side-by-side, a second plurality of circuit boards arranged generally side-by-side and a midplane having a first main surface and a second main surface. The first plurality of circuit boards is mounted to the midplane at the first main surface and the second plurality of circuit boards is mounted to the midplane at the second main surface. The first plurality of circuit boards is in a non-parallel relationship relative to the second plurality of circuit boards.
The midplane has a void area extending completely from the first main surface to the second main surface. A first circuit board from the first plurality of circuit boards intersects the void area at the first main surface and a second circuit board from the second plurality of circuit boards intersects the void area at the second main surface. Electrical pathways extend from the first circuit board to the second circuit board through the void area, the electrical pathways establishing a data communicative relationship between the first circuit board and the second circuit board.